High-performance charge-pump circuit for phase-locked loops

摘要

One of the high-performance charge-pump circuits basically includes two switch mirror circuits, two current sources, two switches, and an inverter. In the switch mirror, the switch coupled to the diode-connected reference transistor is indirectly mirrored to the output. The great advantage is to utilize the switch mirrors as a part of building cascodes at the output. Consequently, all high-performance charge-pump circuits suppress any charge-injection errors, reduce charge-pump offset, increase the output impedance for effective current injection, and reduce chare-sharing problem.